Method of producing rubber coated fabrics



Aug. 39, 19533. E. A. MURPHY 3 METHOD OF PRODUCING RUBBER COATED FABRICS Filed April 3, 1936 INVENTOR 15.7mm E0 Al? THL f? MURPHY BY 6; W ATTORNEY Patented Aug. 30, 1938 UNITED STATES PATENT OFFICE Edward Arthur Murphy,

assignor to Dunlop Rubber Comham, England,

Wylde Green, Birmingpany, Limited, London, England, a British comv pany Application April 3, 1936, Serial No. 72,494 In Great Britain June 7, 1935 .4 Claims.

This invention comprises improvements in or relating to the production of fabrics treated with waterproof compositions of or containing rubber as, for instance, waterproofed fabrics, impregnated weftless cord fabrics, substitutes for cork, leather, linoleum and rubber-backed carp ts.

The present invention is an improvement in or modification of the manufacture described and claimed in Patent No. 2,007,578. In said patent there is described and claimed a method which permits continuous production of rubber sheet wherein aqueous dispersions of rubber material are introduced into a nip or nips formed by two or more moving rounded surfaces, co-.

agulation of the aqueous dispersions aforesaid being effected in such manner that coagulation commences on the introduction of the dispersions between the moving surfaces forming the nips or receptacles and proceeds thereafter and the material withdrawn through the nip or nips.

In my co-pending application Serial No. 44,390 filed October 10, 1935, there is described a modification of the method as set forth in Patent No. 2,007,578 which permits continuous production in sheet form of materials of or provided with rubber or similar material of sponge-like or cellular structure from aqueous emulsions or dispersions of the kinds specified therein. The modified method comprises introducing. frothed aqueous emulsions or dispersions of the kinds specified therein into one or more nips of one or more receptacles formed or partially formed by positioning two or more moving surfaces, effecting coagulation of the foamed aqueous dispersions aforesaid in such manner that coagulation commences on the introduction of the foamed dispersions between the' moving surfaces forming the nips or receptacles and proceeds thereafter, and withdrawing the formed material through the one or more nips or receptacles.

The main object of the invention is to overcome difficulties in connection with the proofing of fabrics with aqueous dispersions of or containing rubber.

The use of an aqueous dispersion of or contairiing rubber for spreading on fabrics is well known.

One of the chief disadvantages, however, in connection with the proofing of fabrics with rubber latex is the tendency of the rubber latex to strike through the fabric, making it frequently necessary to treat the fabric with a suitable plastic, for instance, rubber or rosin dissolved in a suitable volatile solvent.

Alternatively, it has been proposed to employ a very small bank of latex paste behind. the doctor knife which is set at an obtuse angle, and to pass the fabric under the knife in such a way that the fabric is not pressed too strongly against it.

Instead of employing rubber latex as such, it has also been proposed to apply to the fabric fiocculent precipitates of or containing rubber produced by the coagulation of aqueous dispersions preferably employed at such dilutions that 100 ccs. thereof contain not more than 10 grams of total solids. I

.In co-pending application Serial No. 70,162 there is described an improved process for the manufacture of fabrics coated with waterproof compositions of or containing rubber which comprises applying to the fabrics froths or foams produced from aqueous dispersions of the kinds specified therein, destroying the frothy or foamy nature of the dispersion while regulating the thickness thereof and thereupon setting the substantially non-frothy or non-foamy layer of dispersion produced. In this way, striking through is prevented. According to an embodiment of this improved process, a carded web of cotton can be fed into the nip of a pair of coagulantlicked rollers as described in Patent 2,007,578.

I have now found that striking through can be prevented when waterproofing fabrics with aqueous dispersions of rubber without it being necessary to employ latex froths or foams although, if desired, latex froths or foams can be employed.

According to the present invention theimproved process for the manufacture of fabrics treated with waterproof compositions of or containing rubber comprises forming one or more nips by positioning two or more moving surfaces, feeding fabric into the one or more nips, applying aqueous emulsions or dispersions of the kinds hereinafter specified to one or more of the said moving surfaces so as to form a layer of emulsion or dispersion on one or more of said moving surfaces, effecting coagulation of the one or more layers of emulsion or dispersion aforesaid prior to their entrance into the nips and in such manner that coagulation proceeds from the said one or more moving surfaces, and withdrawing the treated fabric through the one or more nips.

The one or more nips can, for example, be formed. by positioning two or more rotating rollers, or by positioning two endless belts, or one endless belt and one roller, or by positioning two or more moving lengths of fabric, or by introducing two or more moving lengths of fabric positioned at the desired angles to each other through two,rotating rollers, or by introducing a moving length of fabric between two rotating rollers.

invention, aqueous dispersions of the kinds hereinafter specified can be employed which are, or which have been, rendered capable of gelling or coagulating, upon the application of heat in conjunction with two or more heated moving or rotating surfaces, such as heated rollers. If desired, two or more embodiments of the present invention can be used in combination.

Where coagulant-licked rollers are employed, these most suitably take the form of rubbercovered rollers, the rubber covering being of a hard nature, and preventing corrosion due to any attack by the coagulant. The rollers are geared together and may be hand or motor driven. The

licking with coagulant may be achieved, for example, by the use of felt wicks soaked in coagulant or by rollers rotating in coagulant baths and in contact with the processing rollers.

Any'suitable known coagulant may be employed, for example, aqueous acetic acid solutions, coagulating solutions of salts, e. g., of magnesium sulphate. Volatile coagulants may also be employed.

By the term fabric is included, for example,

spun and woven material, a plurality of parallel cords, carded material such as cotton, wool or silk and rayon and felted materials. The various features of the invention are illustrated in connection with the accompanying drawing which shows diagrammatically apparatus for passing fabric through the nip between a pair" of rotating coagulating rollers on one of which is spread a layer, somewhat in advance of its contact with the fabric, of compounded latex or other aqueous dispersion of rubber.

In the embodiment of the invention shown in the accompanying drawing, a fabric Ill, for example, a normal proofing fabric is fed into the nip of two rubber covered rollers II and i2 licked with acetic acid (10% aqueous solution) by means of coating rollers i3 and II dipping in acetic acid tanks l5 and i6.

A latex mixing for example of composition Parts by weight Rubber 100 Sulphur 2 Mineral oil 5 Accelerator 1 Zing mrirle 1 to the fabric and a satisfactory proofing results.

The weight of coagulated material applied per unit area is controlled by the strength of the acid, the distance from the point of application of the latex to the nip and the time required to traverse this distance. Drying and vulcanizing proceed subsequently in known manner.

The emulsions or dispersions of rubber or the like comprise those consisting of rubber, guttapercha, balata or similar vegetable resins occurring naturally or artificially obtained. Such artificial aqueous dispersions may include those of coagulated rubber, vulcanized rubber, synthetic rubber, waste or reclaim.

If desired, any of the aforementioned dispersions may be used alone or in admixture with one another.

Any of the aforesaid dispersions may contain the usual known compounding and vulcanizing ingredients and/or may be in the first instance in concentrated form.

Concentrates such as are obtained in Patent No. 1,846,186 and in British Patent No. 219,635, to which may be added any one or more of the usual known compounding ingredients, may also be employed.

If desired, the aqueous dispersions employed are or have been made capable of gelling on the application of heat. Examples of substances which can be used for making the aforesaid dispersions capable of gelling on the application of heat are sodium or potassium silicofluoride, ammonium persulphate, or reagents which by chemical interaction with one another upon the application of heat, produce one or more substances in situ which function as active coagulating agents, for example, a mixture of zinc oxide and ammonium sulphate.

If desired, any of the aforesaid emulsions or dispersions can be employed in a frothed condicordance with the present invention, fabrics provided with rubber or similar material of spongelike or cellular structure.

What I claim is- 1. A process for the manufacture of fabrics treated with a composition of or containing, rubber which comprises forming a nip between a pair of moving surfaces, feeding fabric into said nip in the direction of movement of said feeding surfaces, applying an aqueous dispersion of rub- 'ber composition to one of said moving surfaces in advance of its contact with said fabric, so as to form a layer of dispersion on said moving surface, substantially completely coagulating said layer progressively from the face thereof resting on said moving surface to substantially its outer face prior to its entrance into said nip, passing said layer into contact with said fabric in said nip immediately upon coagulation and while still wet to transfer said layer to said fabric, withdrawing the treated fabric through said nip and thereafter drying and vulcanizing the resulting structure.

'2. A process for the manufacture of fabrics treated with a composition of,. or containing; rubber which comprises forming a. nip between a pair of surfaces, at least one of which surfaces moves toward said nip, feeding fabric into said nip in the direction of movement of said moving 76 surface, applying an aqueous dispersion of rubbercomposition to said moving surface in advance of its contact with said fabric, so as to form a layer of dispersion on said moving surface, substantially completely coagulating said layer progressively from the face thereof resting on said moving surface to substantially its outer face prior to its entrance into said nip, passing said layer into contact with said fabric in said nip immediately upon coagulation and while still wet to transfer said layer to'said fabric, withdrawing and vulcanizing the resulting structure. 3. A process as claimed in claim 1 wherein the nip is formed by two rotating cylindrical surfaces.

4. A process as claimed in claim 1 wherein aqueous dispersions are employed which are capable of gelling or coagulating upon the applicationof heat and in which the surfaces forming.

the nip are heated.

EDWARD ARTHUR MURPHY. 

